1. Field of the Invention
The present invention relates to efficiently deriving end products from biomass. In particular, the present invention relates to methods of generating end products from algae biomass and the derived products therefrom.
2. Description of the Prior Art
Biomass grown in high moisture environments such as microalgae, macroalgae, and cyanobacteria is a promising source of plant-derived primary and secondary metabolites, useful for deriving products such as biofuels and other valuable end products. In the right conditions, these aquatic organisms utilize carbon and nutrients to rapidly grow biomass containing proteins, carbohydrates, and compounds containing energy reserves in the form of long chain oxygenated hydrocarbons (such as fatty acids and glycerides—lipids) and long chain non-oxygenated hydrocarbons (such as carotenoids and waxes) and value-added organics (that have higher valued uses than fuels such as neutraceutical antioxidants) within the cellular material.
The lipids, once isolated and purified, present an excellent feedstock for a variety of liquid fuel production alternatives. Lipids fractionated from biomass can be used directly as liquid fuel feedstocks, or they can have higher value uses such as omega-3 fatty acids being used as nutritional additives. For example, biomass-derived lipids can be a viable feedstock to traditional refining operations producing products such as straight chain alkanes suitable as a direct replacement product to gasoline. Alternatively, lipids such as triglycerides can be reacted to directly form esters and selectively utilized as a biodiesel liquid fuel, replacing current edible oils being used to produce biodiesel.
The biomass metabolites traditionally not considered lipids, such as proteins and carbohydrates, have many alternative applications, including use as a feedstock for biological production systems, plastic additives (glycols from biomass sugars), use in animal nutrition as a feed, and in other fuel producing alternatives (syngas production, methane production by anaerobic digestion, ethanol production via fermentation, etc.).
Microalgae have the potential to be a major source of biofuels and biochemicals worldwide and are unique in the rapid sequestering carbon dioxide. Among other advantageous attributes, microalgae grow at a rapid pace, they are able to grow in very inhospitable conditions, they are not typically considered a human food source, and land and water use for growing microalgae is typically not competitive with land and water required for conventional food production. Microalgae production for liquid fuels and carbon sequestering is a revolutionary renewable biofuel platform. Microalgae have the potential to transform the energy industry by supplying cost transformational biofuel production systems, and novel applications of existing technologies to improve the production cost to a point competitive with fossil fuels. It is possible to produce more than ten times more oil per acre with microalgae than other biofuel crops such as palm oil.
The metabolic mechanisms of algae produce hundreds of biochemical compounds that are within the unicellular organism and typically are structurally part of the organism.
The major classes of cultivated algae and weight percentage of each class are as follows (dry weight): Lipids, triglycerides, fatty acids: 20-40%
Unsaponifiabes: non polar C14-C24 (10%-20%) and polar (10%-20%);
Proteins: 30%-35%.
Carbohydrates (as a blend of polysaccharides) 15%-20%.
Other—salts, organo-metallics, inorganics: 1-5%.
The challenge to algae commercialization is the total economics of land, capital equipment, operational costs, and product slate revenues. Chief among the challenges is the ability to effectively collect and isolate the valuable cell metabolites including lipids, carbohydrates, and proteins. Isolation of the compounds as opposed to comingled slurry creates value enabling concentrated streams, fuel conversion processes, and numerous focused applications of the many and varied algae metabolites.
In addition to collection and concentration of cell compounds and derivatives, critical to large-scale microalgae production is the ability to close loop residual fixed carbon, fixed nitrogen, valuable nutrients (phosphorus, potassium and trace mineral such as iron magnesium, etc) and the water. Recycling these key production ingredients is crucial to the overall energy and carbon balance for large-scale algae production operations.
Historically, high moisture biomass production systems have been designed for specific low volume product production. Prior art supplies consideration for techniques to isolate individual compounds. The prior art is predominantly focus on high value single product isolation and extraction techniques. The prior art (e.g. U.S. Pat. No. 5,539,133 to Kohn et al., U.S. Pat. No. 6,258,964 to Nakajima et al., U.S. Pat. No. 6,166,231 to Hoeksema, U.S. Pat. No. 6,180,376 to Liddell, U.S. Patent Application No. 2009/0004715 to Trimbur et al., U.S. Patent Application No. 2008/0155888 to Vick et al.) has focused on lipid fractionation. Post-lipid fractionation, the “waste” algae biomass are typically discarded or made into biogas (methane) using digesters without further fractionation of the remaining valuable products.
More specifically, U.S. Pat. No. 5,324,658 to Cox, et al. discloses a method of preparing a hydrolysate by (a) forming an aqueous slurry of algae, (b) rupturing the cell walls of the algae, (c) adding to the algae sufficient acid to form an acid concentration of about 2 to about 3M and then partially hydrolyzing proteins in the algae, (d) discarding the acid-insoluble fraction from the acid-soluble fraction of the resultant hydrolysate, (e) removing the acid from the soluble fraction until the fraction has a pH of at least about 1.0, and (f) titrating the hydrolysate with a base to convert any remaining acid in the hydrolysate to a salt and adjust the pH to within the range of about 6.5 to about 7.0. While a hydrolysate is formed, this method requires the conventional step of rupturing the cell wall before hydrolysis. This process is basically derived from the same process that is used to obtain biofuels from corn. Furthermore, while lipids can be derived from this process, the other valuable products are merely discarded because there is no fractionation involved.
U.S. Pat. No. 4,417,415 to Cysewski, et al. discloses a process for culturing microalgae and fractionating a polysaccharide therefrom. To extract the polysaccharide from the culture, the culture is brought to a pH of about 10 to about 14 and is heated to at least about 80 degrees C. for at least about 20 minutes. The culture is then cooled to not more than about 40 degrees C. and made nonalkaline with acid. After the addition of the acid, a water-miscible organic solvent is added to the culture in an amount sufficient to cause polysaccharide to precipitate therefrom and the resultant precipitated polysaccharide is separated from the accompanying liquid. Again, while polysaccharides can be fractionated, none of the other useful products are obtained because there is no fractionation.
U.S. Pat. No. 6,936,110 to Van Thorre discloses a conventional method for fractionating protein, oil and starch from grain. The method includes providing kernels or seeds comprising a germ and pericarp comprising protein, oil, and starch; steeping the kernels or seeds in a steeping reactor for a time effective to soften the kernels and seeds; milling the steeped corn kernels to separate the germ from the starch/pericarp forming a germ stream and a starch/pericarp stream; subjecting the germ to rapid pressurization/depressurization in order to extract oil and protein from the germ; and separating the starch from the pericarp. This is a typical wet milling process that can be employed for algae as well; however, it is a high energy process and requires substantial modifications in order to be used with algae.
WO/2010/000416 to D'Addario, et al. describes the extraction of fatty acids from algal biomass comprising: producing an aqueous suspension of algal biomass; subjecting the aqueous suspension of algal biomass to acid hydrolysis and extraction by the addition of at least one non-polar organic solvent and at least one inorganic acid under atmospheric pressure to said aqueous suspension of algal biomass, so as to obtain the following three phases: (i) a semisolid phase comprising a slurry of the algal biomass; (ii) an aqueous phase comprising inorganic compounds and hydrophilic organic compounds; (iii) an organic phase comprising fatty acids and hydrophobic organic compounds other than said fatty acids. It is required that the solvent and the acid be added at the same time and that the process be performed at a temperature below 100° C. By combining and limiting these operating conditions, WO/2010/000416 cannot fully extract the cell products from the algal biomass.
State-of-the-art patents tend to focus on specific classes of products such as lipids or polysaccharides or specific products such as DHA as specific polyunsaturated fatty acid. State-of-the-art patents tend not to address at all fractionation platforms addressing the practical need of not only isolating the target classes or product but addressing the need for recovering and or using all non-target materials.
Therefore, there is not only a need for an efficient and inexpensive method of raising algae, but there is a need for an efficient and flexible fractionation platform that can achieve success at isolating classes and specific products and in addition recover on a large scale all valuable products efficiently from the algal biomass.
A novel fractionation platform is articulated as the present invention that is a paradigm shift away from the prior art as it allows not only extraction of target classes and products but to recovery by-products and recycle critical nutrients and water. The present invention provides for a flexible and efficient fractionation platform that will allow not only targeted product isolation and preconditioning the products, but by-products to be effectively separated as classes and specific products with ultimately even nutrients and water to be recycled.